<PRE><B>Question 864092</B>
1)
35 is the initial velocity
4 is the height when served

h=4+35t-16t^2
2)
0=4+35t-16t^2
it is in the air from the serve till it hits the floor
at t = 2.2964
3) vertex 
t=-b/2a

t=-35/2*-16=35/32
plug in 35/32 for t
h=4+35t-16t^2
h = 1481/64 maximum height
0 is the minimum height when it hits the floor
0=4+35t-16t^2
at t = 2.2964
4) 

7.5=4+35t-16t^2
from t = 0.105044 to t = 2.08246</PRE>